As a hot-spot research subject in today's communication standardization field, NGN adopts packet technologies as the carrier network technology to converge fixed communication technology and mobile communication technology. NGN can provide more abundant multimedia services, such as emerging services with real-time requirement (e.g. VoIP, video conferencing, multimedia remote teaching and video-on-demand), these services require the communication network to provide highly efficient end-to-end Quality of Service (QoS) support, and meanwhile the customer has increasingly higher requirements on network service quality. Therefore, how to provide end-to-end QoS support may be one of the core issues of NGN.
As the telecommunication standardization sector of International Telecommunication Union (ITU), ITU-T has made the standards on resource and admission control. The latest draft of Resource and Admission Control Functions (RACF) issued by ITU-T in September 2008 provides the function framework of RACF, as shown in FIG. 1. The RACF consists of two parts which are Policy Decision Functional Entity (PD-FE) and Transport Resource Control Functional Entity (TRC-FE).
The PD-FE is independent of the transport technology and Service Control Functions (SCF). The PD-FE makes a final decision for resource and admission control based on network policy rules, service information provided by the SCF, transport layer subscription information provided by Network Attachment Control Functions (NACF) as well as resource availability policy result information provided by the TRC-FE.
The TRC-FE is independent of service, but is dependent on transport technology. The TRC-FE is responsible for collecting and maintaining the transport network information and resource status information. After receiving resource request from the PD-FE, the TRC-FE enforces resource-based admission control based on QoS, priority demand, resource availability information and transport-related policy rule information.
The transport function consists of Policy Enforcement Functional Entity (PE-FE) and Transport Resource Enforcement Functional Entity (TRE-FE). The PE-FE is a packet-to-packet gateway which may be located between a Customer Premises Network (CPN) and the access network, between the access network and the core network or between different operator networks, and is the key node supporting dynamic QoS control, port address translation control and Network Address Translator (NAT). The TRE-FE enforces the transport resource policy rules sent down by the TRC-FE. The scope, function and Rn interface of the TRE-FE, which need further research, are not the research object of R2 stage.
Functions of each entity in RACF and transport function as well as collaboration relationship between those entities are described in conjunction with FIG. 1.
PD-FE is a policy decision functional entity, which makes preliminary QoS resource decisions based on media flow session information (obtained from SCF via Rs interface), customer transport resource subscription information (obtained from NACF via Ru interface), and then interacts with TRC-FE to confirm whether there are sufficient QoS resource, and finally makes a final admission decision and sends down the decision to PE-FE for enforcement.
The TRC-FE is mainly used for resource control, which monitors resources in network and collects relevant information, and responds as per specific resource conditions when the PD-FE requests resources.
The PE-FE performs policy control (gating, bandwidth, traffic classification and tagging, traffic shaping, QoS mapping of Layer 2 and Layer 3, and collecting and reporting resource utilization information, etc.) primarily under the direction of the PD-FE.
In current description of protocols, the TRE-FE performs policy enforcement of Layer 2 under the direction of the TRC-FE, but neither its specific function nor its scope has been determined.
Currently, customer has more flourishing demands for home safety and entertainment services such as video surveillance, network game, P2P transmission and IPTV. To favorably support such services featuring high rate and high service requirements and high safety, operators need to perform QoS control on home network. Home gateway is the core constituent in home network. The home gateway, which connects the home network devices and external network, is the physical interface for interconnectivity between home internal network and all external networks.
Under non-nomadic/non-roaming scenario, the PD-FE in RACF controls CPN Gateway Policy Enforcement Functional Entity (CGPE-FE) via Rh interface to realize the control of home network.
With respect to home network control in Wholesale scenario, the existing technology is not yet able to offer corresponding solution. In the Wholesale scenario as shown in FIG. 2, one party is the network operator wholesaling network layers as infrastructure to multiple service providers; the other party is the service provider providing different types of network services. The network operator who is like the wholesaler of network resource does not provide services, and service provider who is like the service Retail only provides services. To distinguish the functional entities with the same names between network operator and service operator, the name of an entity in Wholesale scenario is prefixed with (W) to identify that the entity belongs to network operator, while an entity prefixed with (R) belongs to service provider. When a customer is under scenario of Wholesale, the customer uses network access of network operator to access the network and enjoy services provided by service provider.
In the Wholesale scenario as shown in FIG. 2, the SCF belongs to an NGN service provider, and the PD-PE in the NGN service provider interacts with the PD-FE in an NGN network operator via Ri interface. The existing technology has not clearly defined the resource and admission control scheme for home network in light of the Wholesale scenario described above. When a service provider does not provide corresponding resource and admission control, it is difficult to guarantee the network service quality for multimedia service used by the customer, thereby the customer experience and system efficiency are impaired.